diff --git a/tidy3d/components/data/monitor_data.py b/tidy3d/components/data/monitor_data.py
index 5b55ffccdd..6f097ce8d0 100644
--- a/tidy3d/components/data/monitor_data.py
+++ b/tidy3d/components/data/monitor_data.py
@@ -2225,9 +2225,11 @@ def power(self) -> xr.DataArray:
         ``xarray.DataArray``
             Power at points relative to the local origin.
         """
-        power_theta = 0.5 * np.real(self.Etheta.values * np.conj(self.Hphi.values))
-        power_phi = 0.5 * np.real(-self.Ephi.values * np.conj(self.Htheta.values))
-        power = power_theta + power_phi
+        fc = self.fields_cartesian
+        Sx = 0.5 * np.real(fc.Ey * np.conj(fc.Hz) - fc.Ez * np.conj(fc.Hy))
+        Sy = 0.5 * np.real(fc.Ez * np.conj(fc.Hx) - fc.Ex * np.conj(fc.Hz))
+        Sz = 0.5 * np.real(fc.Ex * np.conj(fc.Hy) - fc.Ey * np.conj(fc.Hx))
+        power = Sx + Sy + Sz
 
         return self.make_data_array(data=power)